Most users don't realize how noisy m43 sensor are in DSLR terms because there's a lot of NR being applied to the JPEGs. But once you compare to good APS-C output in LR the rather dramatic increase in noise at base ISO is apparent. Fortunately Olympus and Panasonic has filtered what is possible through a recognition that IQ must compete with DSLRs before the platform is tractable.

You are right that there is still a difference of about one EV in base-ISO shadow noise (effectively indexed by DR) between the very best (rather than average) APS-C sensors and the current generation of MFT sensors. But if you expose optimally (ETTR), current MFT sensors are already good enough that this difference is hardly noticeable except for high-DR scenes where you have to push the shadows in PP. And for such scenes, you can often solve the problem by bracketing exposure and then merging/aligning the images in PP.

What is your factual basis for this? What is 'hardly noticeable'?

See examples below.

What is 'high-DR'?

What I talked about was "high-DR scenes where you have to push shadows in PP". See exemplification below.

What is 'often'?

In this case, I take "often" to mean at least 50 percent of the time.

Below you find examples of three scenes. The first is an example of a scene with low DR. The second is an example of a scene with high DR (requiring a bit of shadow pushing if you expose so as not to clip the highlights) but not so demanding that it is beyond what the E-M5 sensor can manage in a single shot. The third is an example of a scene whose DR is far beyond what the E-M5 sensor can manage (unless you accept that much of the scene goes impenetrably black). It is the result of blending nine different shots with one EV difference in exposure between each shot.